BLAZING FURY: Firefighters battle an East 14th Street fire that started yesterday when a worker named Esteban (inset) had a welding accident.William Farrington

A worker installing a fire-safety door sparked a massive three-alarm blaze that ripped through five stores in Stuyvesant Town yesterday.

The building housing the five stores at 500 E. 14th St., across from the Stuyvesant Town complex, was gutted. Buildings Department inspectors were on the scene last night to check the stability of the structure’s remains.

An employee of Ideal Fire Safety Systems said he was working on a fire-access door in the kitchen of Pete’s-A-Place, a pizza joint, at around 10:15 a.m. when his welding torch apparently set some grease on fire.

The blaze spread “like wildfire,” said the worker, who gave his name as Esteban.

“I had three fire extinguishers, and it didn’t help any. By the time I put one section out, another went up,” Esteban said.

“Of course it happens to me,” he said ruefully. “But I tried to stop it. I really did.”

Esteban, who has worked for Ideal for 10 years, said he feared the accident would cost him his job.

He was expecting to spend his workday on another assignment when his boss told him to install the pizza-shop door at 8 a.m. The door was supposed to be finished by yesterday afternoon, in time for a Fire Department inspection.

Workers at Stuyvesant Convenience learned they were in danger when a customer ran into the store and warned everyone to “get the heck out,” said employee Adal Murshed, 35.

Essa Assabahi, 29, another store worker, watched helplessly from across the street as the business went up in flames. “That’s my job right there,” he said. “Now I’m unemployed.”

Flames shot up through the building’s roof, and smoke was visible from blocks away. It took 140 firefighters to extinguish the blaze. Two were treated for smoke inhalation.